LONDON 
As the sun set on the opening week of Wimbledon, just about the only seeding that truly signified something was No. 1.

That’s the number beside the names of Serena Williams and Novak Djokovic, who turned in nearly perfect performances back-to-back Saturday on Centre Court to cap nearly perfect runs to the fourth round at the All England Club, while chaos reigned all around them during the first week.

In the final match of the fortnight’s first half, played with the roof closed and lights glowing to make sure it would get done as darkness approached, defending champion Williams used eight aces and 11 return winners to power past 42-year-old Kimiko Date-Krumm of Japan 6-2, 6-0 in 61 minutes.

“She didn’t lose energy, and her game, I think, is getting better, day after day. Not better in general, but adapting to the surface. Everything is getting better,” said French coach Patrick Mouratoglou, who has been working with Williams over the last year, when she is 77-3. “So now let’s enter into the most important part of the tournament. ... Now the matches are going to get tougher and tougher.”

Might not necessarily have been a fair fight, considering that Date-Krumm is ranked 84th and was the oldest woman to reach the third round at Wimbledon in the 45-year Open era. Never better than a semifinalist at a Grand Slam tournament, she played Williams evenly for about three games, before the 16-time major champion took over.

“She has so much power, speed,” Date-Krumm said. “She has everything.”

Williams’ easy win followed the 6-3, 6-2, 6-2 victory over 28th-seeded Jeremy Chardy of France turned in by 2011 champion Djokovic, who compiled a remarkable ratio of 38 winners to three unforced errors. The Serb’s initial miscue of his own doing did not come until the third set’s sixth game, when he double-faulted while ahead 4-1, 40-love.

“Everything went my way,” Djokovic said. “I did everything I wanted to do.”

Sabine Lisicki, the 23rd-seeded German, will meet Williams on Monday for a quarterfinal berth.

Up next for Djokovic after the middle Sunday’s traditional day of rest is another German, 13th-seeded Tommy Haas, the 35-year-old who is enjoying a career renaissance and eliminated Feliciano Lopez of Spain 4-6, 6-2, 7-5, 6-4.

How certain was Lisicki that she would be dealing with Williams and not Date-Krumm? Lisicki tweeted a photo of her with Haas early in the second set of Williams’ match, writing: “Last Germans standing” and “We both play the no1’s next.”